Proteins that selectively bind to selected targets by way of non-covalent interaction play a crucial role as reagents in biotechnology, medicine, bioanalytics as well as in the biological and life sciences in general. Antibodies, i.e. immunoglobulins, are a prominent example of this class of proteins. Despite the manifold needs for such proteins in conjunction with recognition, binding and/or separation of ligands/targets, almost exclusively immunoglobulins are currently used.
Additional proteinaceous binding molecules that have antibody-like functions are the members of the lipocalin family, which have naturally evolved to bind ligands. Lipocalins occur in many organisms, including vertebrates, insects, plants and bacteria. The members of the lipocalin protein family (Pervaiz, S., & Brew, K. (1987) FASEB J. 1, 209-214) are typically small, secreted proteins and have a single polypeptide chain. They are characterized by a range of different molecular-recognition properties: their ability to bind various, principally hydrophobic molecules (such as retinoids, fatty acids, cholesterols, prostaglandins, biliverdins, pheromones, tastants, and odorants), their binding to specific cell-surface receptors and their formation of macromolecular complexes. Although they have, in the past, been classified primarily as transport proteins, it is now clear that the lipocalins fulfill a variety of physiological functions. These include roles in retinol transport, olfaction, pheromone signaling, and the synthesis of prostaglandins. The lipocalins have also been implicated in the regulation of the immune response and the mediation of cell homoeostasis (reviewed, for example, in Flower, D. R. (1996) Biochem. J. 318, 1-14 and Flower, D. R. et al. (2000) Biochim. Biophys. Acta 1482, 9-24).
The lipocalins share unusually low levels of overall sequence conservation, often with sequence identities of less than 20%. In strong contrast, their overall folding pattern is highly conserved. The central part of the lipocalin structure consists of a single eight-stranded anti-parallel β-sheet closed back on itself to form a continuously hydrogen-bonded β-barrel. This β-barrel forms a central cavity. One end of the barrel is sterically blocked by the N-terminal peptide segment that runs across its bottom as well as three peptide loops connecting the β-strands. The other end of the β-barrel is open to the solvent and encompasses a target-binding site, which is formed by four flexible peptide loops. It is this diversity of the loops in the otherwise rigid lipocalin scaffold that gives rise to a variety of different binding modes each capable of accommodating targets of different size, shape, and chemical character (reviewed, e.g., in Flower, D. R. (1996), supra; Flower, D. R. et al. (2000), supra, or Skerra, A. (2000) Biochim. Biophys. Acta 1482, 337-350).
Various PCT publications (e.g., WO 99/16873, WO 00/75308, WO 03/029463, WO 03/029471 and WO 2005/19256) disclose how muteins of various lipocalins (e.g. tear lipocalin and hNGAL lipocalin) can be constructed to exhibit a high affinity and specificity against a target that is different than a natural ligand of a wild type lipocalin. This can be done, for example, by mutating one or more amino acid positions of at least one of the four peptide loops. In addition, PCT publication WO 2011/154420 teaches one or more methods for producing lipocalin muteins, which bind to IL-4 receptor subunit alpha.
Th2 cytokines IL-4 (officially known as Interleukin-4, Uniprot #P05112) and IL-13 (officially known as Interleukin-13, Uniprot #P35225) have largely overlapping functions and directly promote several key features of asthma including eosinophilia, goblet cell metaplasia, airway hyperresponisveness, IgE immunoglobin switch, alternative macrophage activation, smooth muscle cell remodeling and subepithelial fibrosis. Furthermore, genetic polymorphism in the genes of IL-4, IL-13, IL-4RA (officially known as Interleukin-4 receptor subunit alpha, Uniprot #P24394, SEQ ID NO: 12) and Stat6 are linked with Asthma. This is particular relevant as the combination of allelic variant of IL-4, IL-13, IL-4RA and Stat6 appear synergistic and described polymorphism in IL-4, IL-13 and IL-4RA enhance the production, function or signaling activity of the Th2 cytokines or common subunit of the IL-4/IL-13 receptor (Finkelman et al. JI, 2010, 184:1663-74). Recently, asthma endotypes or subphenotypes have been defined by molecular mechanism or treatment response. Woodruff et al for example defined asthma phenotypes into Th2-high and Th2-low based on the lung epithelial expression of IL-13-inducible genes POSTN (periostin), CLCA1 (gobs) and SERPINB2 (Wooddruff P G et al, Genome-wide profiling identifies epithelial cell genes associated with asthma and with treatment response to corticosteroids PNAS, 2007, 104: 15858-63; Prescott G. Woodruff) (T-helper Type 2-driven inflammation defines major subphenotypes of Asthma, Am. J. Respir. Crti. Care Med., 2009, 180:388-395).
Therefore, it would be desirable to have improved therapeutic methods involving therapeutically effective amount of a composition comprising muteins of human tear lipocalin, binding to IL-4RA with high binding affinity and therefore inhibiting IL-4 and/or IL-13 from binding to their respective receptors, that exhibit in vivo therapeutic activities in a subject in need thereof. When used in the present application, a subject in need thereof may be a mammal, such as a human, a dog, a mouse, a rat, a pig, an ape such as cynomolgus to name only a few illustrative examples, which is in need of a treatment or prevention of a disorder.